This invention relates to hole saw arbors and more particularly to arbors that are adapted for quick attachment to and release from hole saws and which solves the problem of hole saw wobble.
In the prior art there have been numerous disclosures of quick release hole saw arbors, such as U.S. Pat. No. 3,758,221, dated Sep. 11, 1973, assigned to Black & Decker Manufacturing Company. This patent shows a lock plate and fastener nut for attaching the drive shaft to hole saws of various diameters. Other such arbors are disclosed in U.S. Pat. No. 3,784,316, dated Jan. 8, 1974, and U.S. Pat. No. 3,837,759, dated Sep. 24, 1974, both assigned to Capewell Manufacturing Company, as well as U.S. Pat. No. 4,036,560, dated Jul. 19, 1977, and U.S. Pat. No. 4,148,593, dated Apr. 10, 1979, both assigned to Stanadyne, Inc. While these prior patents show various means for connecting and disconnecting drive arbors from a power source to hole saws of various diameters, they do not solve the problem of hole saw wobble resulting from almost always having to "back-off" the threaded connection between the arbor and the hole saw in order to line up the drive pins of the arbor with the drive holes of the hole saw. In this condition, if one holds the drive end of the arbor and shakes the assembly, the hole saw will wobble in a manner suggestive of a "dinner bell", hence called the "dinner bell" effect.
More recently, U.S. Pat. No. 5,035,550, dated Jul. 30, 1991, assigned to House B.M. Co., Ltd., discloses a mechanism for connecting a hole saw to a drive shaft to solve the wobble problem. In that patent, however, the hole saw is not the conventional type, but is specially designed for that purpose. It is open at both ends and includes a bolt 6 adapted to be screw-fitted in a threaded hole within the hole saw body. While this structure would overcome the problem of hole saw wobble, it could not be use for connection to conventional hole saws which, in sizes of 11/4 inch and larger, have a threaded central bore and radially offset drive holes in the base thereof.
The principal object of this invention is to provide a novel arbor construction for quick and easy attachment to and release from conventional hole saws which overcomes the problem of hole saw wobble.
Another object of this invention is to provide an arbor construction of the above type which enables the threaded central member to be snugly screwed by clockwise rotation into the bore of a hole saw and by continued clockwise rotation of a rotatable drive collar to align its drive pins with the drive holes of the hole saw.